Charles langdon-davies



(No Model.)

0. LANGDON-DAVIES.

APPARATUS FOR THE RHYTHMIG GENERATION 0F ELBGTRIG OURRENTS'.

No. 439,017. Patented Oct. 21, 1890.

UNITED STATES PATENT OFFICE. 7

CHARLES LANGDON-DAVIES, OF LONDON, ENGLAND.

APPARATUS FOR THE RHYTHMIC GENERATION F ELECTRIC CURRENTS.

SPECIFICATION forming part of Letters Patent No. 439,017, dated 0ctober21, 1890.

Application filed August 16, 1889. Serial No. 321,046. (No model.) Patented in England November 10, 1888, No. 16,889; in

France July 25, 1889, No. 199,802; in Belgium July 25, 1889, No. 87,183; in Germany July 30,1889,N0.68,201; in Switzerland August 1, 1889,1lo. 1,360; in Luxemburg August 2, 1889,1l0. 1,163; in Turkey August 14, 1889,1l'o. 150; in Cape of Good Hope August 24, 1889; in Natal August 27, 1889; in Victoria September 6, 1889, No. 7,081; inNew South Wales September 9, 1889,1l0.1,690; in Tasmania September 10, 1889, No. 739/; in South Australia September 10, 1889,1111. 1,409; in New Zealaud September 16, 1889, No. 3,954; in Queensland September 16 and December 27, 1889,1lo. 846; in Italy September 17, 1889, LI, 102; in Transvaal September 25, 1889, No. 118; in Spain September 26, 1889, No. 9,886; in Brazil October 12, 1889,1lo. 776; in Austria-Hungary November 17, 1889,11'0. 38,421 and No. 56,247; in Norway December 18, 1889,1110. 1,440; in India February 21 and March 8, 1890, No. 238/89, and in Western Australia May 3, 1890.

To all whom it may concern.-

Be it known that 1, CHARLES LANGDON- DAVIES, a citizen of England, residing at Mowbray House, Victoria Embankment, in the county of London, England, have invented new and useful Improvements in Apparatus for the Rhythmic Generation of Electric Ourrcnts, (for which I have obtained Letters Patents in Great Britain, dated November 10, 1888, No. 16,339; in France, dated July 25, 1889, No. 199,802; in Belgium, dated July 25, 1889, No. 87,133; in Germany, dated July 30, 1889, No. 53,201; in Italy, dated September 17, 1889, Vol. LI, 102; in Austria-lilungary, dated November 17, 1889, Nos. 33,421 and 56,247; in Norway, dated December 18, 1889, No. 1,440;

' in Spain, dated September 26, 1889,No. 9,886;

in Turkey, dated August 14, 1889, No. 150; in Victoria, dated September 6, 1889, No. 7,081; in New Zealand, dated September 16, 1889, No. 3,954; in New South Vales, dated September 9, 1889, No. 1,690; in Tasmania, dated September 10, 1889, No. 739 10; in South Australia, dated September 10,1889, No. 1,409; in \Vestern Australia, dated May 3, 1890; in Queensland, dated September 16 and December 27, 1889, No. 846; in Natal, dated August 27, 1889; in Cape of Good Hope, dated August 24,1889; in Switzerland, dated August 1, 1889, No. 1,860 in Luxemburg, dated August 2, 1889, No. 1,163; in Brazil, dated October 12, 1889, No. 776 5 in India,dated February 21 andMarch 8, 1890, No. 238/89, and in Transvaal, dated September 25, 1889, No. 113,) of which the following is a specification, and which is illustrated in the accompanying drawings, in which- Figure 1 is a diagram of a circuit, showing the method heretofore employed for intermitting acircuit. Fig. 2 is a diagram embodying my improved device for rhythmically intermitting the circuit. Figs. 3 and 4 illustrate diagrams of the vibrations of the break, whereby the current is intermitted, but not rhythmically. Fig. 5 shows diagrams of a circuit rhythmically intermitted by my improved device. Figs. 6 and 7 are diagrams illustrating the difference between the usual and rhythmic succession of impulses. Figs. 8, 9, 10, and 11 illustrate various modifications of construction for accomplishing the result contemplated by my invention.

\Vhen it is desired to-generate secondary electric currents at a fixed rate by means of regular interruptions in a primary circuit, or when it is desired to interrupt any electric current at a fixed rate, it is customary to employ as part; of the circuit to be interrupted a pendulum, tuning-fork, reed, or other vibrator whose natural rate of action or vibration is the same as the rate of interruption desired. This organ 1 will term a vibrator.

Fig. 1 is a diagram of such a circuit, comprising a key K, a coil B B, a battery P, a contact-screw S, and a vibrator A. The coil B B is wound round an iron core 0, (and it may be the primary of an induction-coil.) The vibrator A is placed in front of the core 0, and when the circuit is open the vibrator touches the contact-screw S. On closing the circuit-say by means of K-the core 0 attracts the vibrator A away from the screw S,

thereby immediately opening the circuit again at S. The elasticity of the vibrator causes it to return at once to S, closing the circuit, which is instantly opened again, as before. This continues as long as the key K is pressed.

The diagrams in Fig. 3 explain the action of the vibrator under these conditions. Fig. 3 shows the vibrator at rest, and the dotted lines indicate the amplitude of vibration of which it would be capable if it were free. Fig. 3 shows the position of the vibrator when attracted toward the core on the closing of the circuit. Fig. 3 shows its position when it has been brought back by its own elasticity to the screw S. This screw being fixed, the vibrator cannot complete its vibration, but

contact at S, not upon the natural rate of the vibrator, and, further, that the length of such a current bears no necessary relation to the length ofthe interval by which it is separated from the s'ucceding current. Even when the period of interruption bears a relation to the period of the vibration, which is not always the case, the rate of interruption bears no relation to the natural rate of the vibration, because the vibrator before completing one vibration is forced to commence another vibration.

Fig. 6 shows at Fig. 6 the resulting short currents in the primary separated by long intervals, and at Fig. 6 the resultingimpulses in the secondarynamely, two impulses exceedingly close together separated by a long interval. Instead therefore of generating sec ondary impulses separated by regular intervals, these impulses are separated by intervals of Varyinglengths, asbetween one and two and between. two and three. A telephone inserted in a secondary circuit subject to these impulses instead of reporting the clear note due to the vibration of the vibrator produces a harsh and discordant croak. This irregularity has hitherto been a serious disadvantage to harmonic telegraph and other instruments whose perfect action depends upon the rhythmic generation of the currents. It has been sought to overcome the difficulty by placing a light spring upon the vibrator, as is shown diagrammatically in Fig. 4. Fig. 4 shows the position of rest, Fig. 4 the second position when the vibrator is drawn toward the core, Fig. 4 the third position when the vibrator is returning by its own elastic force. If the period and amplitude of each vibration of the spring could be made to correspond exactly with those of the vibrator, so that the spring would naturally move through the same space as the vibrator in the same time, it might be possible to obtain rhythmic action by these means; but such exactitude of construction being practically impossible, rhythmic action is not so obtained. When the spring moves too slowly, it leaves the screw S too soon, Fig. 4., the current is thus too short, and the interval is too long. When the spring moves too quickly, it remains too long upon the screw S, Fig. 4 and then the current is too long and the interval is too short.

My invention relates to means of overcoming these difficulties in the following manner: I arrange the vibrating organ Aso that it shall be as free as possible to vibrate at its natural rate. I prefer to employ it thus solely as a governor without using it as a circuitbreaker. I provide a separate organ to perform the office of circuit-breaker; but the action of this circuit-breaker is governed by that of the vibrator A. I arrange the circuitbreaker so that it remains upon its contactstop for one-half of the period required for a complete vibration of the vibrator, and is kept away from the,contact-stop for the other half period.

Fig. 2 shows a circuit similar to that indicated in Fig. 1, but with the alterations therein required to carry out my invention. A is the vibratory organ as before, but not forming part of the circuit. The work done by the vibrator A in Fig. 1that is to say, the making and breaking of contact-is done by the circuit-breaker V in Fig. 2, which is arranged to touch the screw S. The circuitbreaker V extends beyond the point S, and touches that side of the vibrator A which is nearest .to the core 0'. It is necessary that the circuit-breaker V should bear two proportions as regards the vibrator A, first, the circuit-breaker V must have a period of vibration somewhat less than that of the vibrator A and must tend to move faster; second, the circuit-breakerV must be mechanically weaker than the rate-vibrator A.

The action of the apparatus is as follows: When the circuit is closed by the key K, Fig. 2, the vibrator A, being drawn toward the core, carries away the circuit-breakerV from its contact-screw S, and keeps it away along with the vibrator for one-half of the period of a vibration of the vibrator, as is indicated at Fig. 5". The circuit-breaker, tending to move faster than the vibrator, returns with it to the middle point of vibration S, where the circuit is again completed by the circuitbreaker V and screw S; but the vibratorA is free to leave the circuit-breaker there and to continue its vibration, as indicated at Fig. 5. While it is doing so contact is maintained between V and S during this half of the vibration of the vibrator until it reaches the middle point of vibration again. Thus during the first half of the period of each vibration of the vibrator the circuit-breaker opens and keeps open the circuit, and during the second half of the period of each vibration of the vibrator the circuit-breaker maintains the circuit closed. The moment when the vibrator A receives its magnetic pluck toward the core 0 is the moment when it can best afiord to encounterresistance to its vibration, and this is the only moment when, according to my invention, it receives such resistance. Even this is compensated, because the energy which is stored in the circuitbreaker V when it is being moved toward the core is nearly all given back to the vibrator when it is moving away from the core, so that although one part of its vibration is retarded, another part is accelerated, the whole period being thus adjusted to its normal rate. By

making the circuit-breakerV of steel or iron and placing it at a suitable distance from the core, as in Fig. 2, it receives a small magnetic pluck at the same moment as the vibrator A,

and thus relieves the vibrator from its retarding pressure. The magnetic action of the core upon the vibrator must not, however, be so strong as to overcome the tendency of the vibrator to vibrate at its normal rate. The closing or opening of the circuit being always at the middle point of a vibration, the duration of a primary or direct current is always that of half a vibration, and the duration of the interval is the same as indicated at Fig. 7. The secondary impulses are therefore equidistant in time, as indicated at Fig. 7 Vhen a telephone is put into a circuit governed by this instrument, it gives forth the musical note of the vibrator.

In order to increase the durability of the parts composing the contact at S, it is sometimes desirable to arrange arubbing-contact. This can be done, as shown in Fig; 8, by arranging an additional spring G to take the place of the usual platinum pin in the screw S and connecting the spring by two links to the screw S, so that when V presses upon it the spring G yields a little, and so rubs the point of contact, but is prevented by the attachment to S from followingV into that part of its vibration which is required to keep the circuit open,

Another way is to carry the circuit through the vibrator A, as it was in the ordinary vibrator shown in Fig, 1, and then through the spring V, instead of through the screw. In this case it is necessary to provide a stopl behind the spring V to prevent it from following Ain the direction of the core, as shown in Fig; 9.

Fig. 10 shows how the opening and closing of the circuit may be effected by means of a spring-rocker subject to the action of the vibrator. R is a rocking-piece moving on a pivot P and having its lower side so shaped that after passing its middle position a spring T carries it toward and holds it against the one or the other of two contact-screws S. The vibrator A is engaged in a wedge-shaped recess of the rocker, so adjusted that the rocker is thrown against one of the screws at each half-vibration, where it remains until A, returning, throws it over to the other screw. One of the screws may be merely a stop, or both screws may have such connections that the current through the coil is reversed at each vibration.

Fig. ll shows a modification by which the action of a light spring such as is shown in Fig. 4t may be improved A headed pin P, fixed in the vibrator A, passes through the light spring, permitting the spring to move toward A, but preventing it from moving away from A farther than the head of the pin permits.

Having thus described the nature of my invention and the best means I know for carrying the same into practical effect, I claim- An instrument for generating rhythmic electric currents, consisting of a temporary magnet, a contact-stop, a single circuit-closer, and a vibrator co-operating with the circuitcloser, whereby the periods of transmission and of cessation of impulses are equalized, substantially as described In testimony whereof I have signed my name to this specification, in the presence of two subscribing witnesses, this 29th day of July, A. D. 1889.

C. LANGDON-DAVIES.

Witnesses:

HAROLD IMRAY, Patent Agent, 28 Southampton Buildings,

London, IV. C.

J No, P. M. MILLARD, Clerk to JVIessrs. Abel &' Immy, Consulting Engineers and Patent Agents, 28 Southampton Buildings, London, W. C. 

